Glass Retort: a Blown Bulb with a Long Neck Bent Down

A retort is the old distilling vessel: a round glass bulb whose long neck bends down to a receiver, so the neck itself condenses the vapour. Alchemists used it, and so did Lavoisier and Berzelius before condensers. Blow a bulb on a long tube, bend the tube down in a wide flame, and add a corked filling hole on top. The picture: a mid-19th-century glass retort with a stoppered filling hole (Wellcome Collection).